Is it possible to change the order of objects in a group?
You can sort the group (actually any list type) by using Sort List node:



Tip: You can apply multiple/cascading sorting rules to a list. For example, in my case , I first sorted all objects based on their Y location, then sorted the result again by X location.



Update:

You can try applying round math here for better sorting, due to the precision, for example:

round(e.location.y, 3)

round(e.location.x, 3)